The present disclosed subject matter relates to a method of controlling event-responsive traffic lights at an intersection of lanes by a controller which switches the traffic lights in a sequence of phases. The controller has a memory storing a set of phase sequences and is configured to change from one phase sequence to another. The method comprises, in a server: a) generating candidate sets of phase sequences; b) determining the traffic flows on the lanes; c) calculating a cost measure for each candidate set; and d) sending the candidate set with the lowest cost measure to the controller; in the controller, receiving and storing the sent set in the memory as the set; and repeating steps b)-d). The disclosed subject matter further relates to the server used in said method.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of controlling event-responsive traffic lights at an intersection of lanes in a transportation network by means of: a controller which switches the traffic lights in cycles and, in each cycle, in a sequence of phases, each phase corresponding to a different switching state of the traffic lights and allowing traffic flow on none, one or more of the lanes, wherein the controller has a memory storing a set of phase sequences and is configured to change from one phase sequence of the set to another phase sequence of the set upon detection of a lane-related event, and by means of a central server connected to the controller and to one or more sensors that measure traffic flows on the lanes, the method comprising, in the server: a) generating candidate sets of phase sequences, wherein in each candidate set all phase sequences have a same number of time slots in the same order, each time slot is occupied by a respective phase and time slots of the same order have the same duration, and wherein each candidate set differs in at least one duration of a time slot of a specific order; b) determining the traffic flows on the lanes by means of the one or more sensors; c) calculating a cost measure for each candidate set on the basis of the determined traffic flows on the one hand and the durations on the other hand; and d) sending the candidate set with the lowest cost measure to the controller; in the controller, receiving and storing the sent set in the memory as the set of phase sequences; and repeating steps b)-d) in successive intervals.
2. The method according to claim 1, wherein each of said intervals lasts at least two cycles.
3. The method according to claim 1, wherein the candidate sets are generated such that, in all candidate sets, a specific phase occupies only time slots which each have a minimum duration.
4. The method according to claim 1, wherein the cost measure is an average waiting time.
5. The method according to claim 4, wherein the cost measure is calculated as, D k = C · ∑ j = 1 J ( 1 ∑ i = 1 I q i , j , k · ∑ i = 1 I q i , j , k · ( T c - T g , i , j , k ) 2 ( 1 - q i , j , k s i , j , k ) ), with Dk the cost measure for the k-th candidate set, Tg,i,j,k the duration of the i-th time slot of the j-th phase sequence of the k-th candidate set, qi,j,k the cumulative determined traffic flow on all lanes which allow traffic flow in the phase that occupies the i-th time slot of the j-th phase sequence of the k-th candidate set, si,j,k the cumulative given saturation flow on all lanes which allow traffic flow in the phase that occupies the i-th time slot of the j-th phase sequence of the k-th candidate set, Tc the cycle duration, I the number of time slots in the j-th phase sequence of the k-th candidate set, J the number of phase sequences of the k-th candidate set, and C a constant.
6. The method according to claim 1, wherein the cost measure is an average queue length.
7. The method according to claim 1, wherein the server is connected to a further sensor for measuring a traffic flow on a further lane in the transportation network, and wherein, in said step b) of determining the traffic flows, the traffic flow on the further lane is taken into account.
8. A central server for controlling event-responsive traffic lights at an intersection of lanes in a transportation network, the server being connectable to a controller that switches the traffic lights in cycles and, in each cycle, in a sequence of phases, each phase corresponding to a different switching state of the traffic lights and allowing traffic flow on none, one or more of the lanes, and being connectable to one or more sensors that measure traffic flows on the lanes, wherein the server is configured to: a) generate candidate sets of phase sequences, wherein in each candidate set all phase sequences have a same number of time slots in the same order, each time slot is occupied by a respective phase and time slots of the same order have the same duration, and wherein each candidate set differs in at least one duration of a time slot of a specific order; b) determine the traffic flows on the lanes by means of the one or more sensors; c) calculate a cost measure for each candidate set on the basis of the determined traffic flows on the one hand and the durations on the other hand; and d) send the candidate set with the lowest cost measure to the controller; and to repeat the steps b)-d) in successive intervals.
9. The server according to claim 8, wherein each of said intervals lasts at least two cycles.
10. The server according to claim 8, wherein the server is configured to generate the candidate sets such that, in all candidate sets, a specific phase occupies only time slots which each have a minimum duration.
11. The server according to claim 8, wherein the cost measure is an average waiting time.
12. The server according to claim 11, wherein the server is configured to calculate the cost measure as with, D k = C · ∑ j = 1 J ( 1 ∑ i = 1 I q i , j , k · ∑ i = 1 I q i , j , k · ( T c - T g , i , j , k ) 2 ( 1 - q i , j , k s i , j , k ) ) Dk the cost measure for the k-th candidate set, Tg,i,j,k the duration of the i-th time slot of the j-th phase sequence of the k-th candidate set, qi,j,k the cumulative determined traffic flow on all lanes which allow traffic flow in the phase that occupies the i-th time slot of the j-th phase sequence of the k-th candidate set, si,j,k the cumulative given saturation flow on all lanes which allow traffic flow in the phase that occupies the i-th time slot of the j-th phase sequence of the k-th candidate set, Tc the cycle duration, I the number of time slots in the j-th phase sequence of the k-th candidate set, J the number of phase sequences of the k-th candidate set, and C a constant.
13. The server according to claim 8, wherein the cost measure is an average queue length.
14. The server according to claim 8, wherein the server is connectable to a further sensor for measuring a traffic flow on a further lane in the transportation network, and wherein the server is configured to take into account the traffic flow on the further lane when determining the traffic flows.
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July 6, 2023
May 20, 2025
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